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Sensory Aids for Persons with Visual Impairments

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Sensory Aids for Persons with Visual Impairments

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  1. Sensory Aids for Persons with Visual Impairments Cook and Hussey, Chapter 8 Damian Gordon

  2. Recall from a previous lecture What is Assistive Technology? • “Any product, instrument, equipment or technical system used by a disabled or elderly person, made specially or existing on the market, aimed to prevent, compensate, relieve or neutralise the deficiency, the inability or the handicap.” International ISO-9999 Standard

  3. Last Week

  4. Introduction • Patients with low vision were surveyed to determine their needs for AT • 149 individuals participated • The age range was 51-96 years (mean age was 76 years old) • Two thirds were male

  5. Introduction • The highest priority items were; • Under the heading of Travel • Finding a clear path, identifying landmarks, recognizing traffic signals, stepping off the curb • Under the heading of Self-Care • Applying make-up, shaving • Under the heading of Reading • Large print, signs, finding the correct food in the kitchen • Under the heading of Recreation • Television, recognizing people’s faces.

  6. HAAT Model Environmental Interface Processor HTI Activity Output Activity Human Context

  7. Sensory Data Sensory Aids Environmental Interface Environment HTI Processor

  8. Principles of Computer Adaptations • Computer interaction is bidirectional • User output is typically achieved by Visual Display • This is sometimes called Soft Copy • When output is produced from a printer, it is called Hard Copy • Computers can also provide auditory outputs in a range of ways • sounds, • beeps, • music, • synthesised speech.

  9. Types of Visual Impairment

  10. Types of Visual Impairments • Low Vision: An individual is able to use a visual display but the standard size, contrast or spacing is inadequate. (augmented technology) • Blind: An individual for whom a visual display does not provide a useful input or output. (alternative technology – may be audition [hearing] or touch) • Some specific conditions: on the following slides...

  11. Myopia and Hypermetropia • Myopia • (short-sighted) Hypermetropia (long-sighted)

  12. Macular degeneration

  13. Tunnel vision

  14. Diabetic retinopathy

  15. Cataracts

  16. Graphic User Interface

  17. Graphic User Interface • GUI allows non-disabled users through the keyboard or mouse for input and a visual display or speakers for output. • The GUI has three features; • A mouse pointer which is moved across the screen • The use of graphical menus and icons • One of more windows

  18. Graphic User Interface • The GUI is design to save typing, reduce effort, and increases accuracy. • The use of icons generally helps with recall and ease of use. • Multiple windows can overlap.

  19. Graphic User Interface • The GUI has both advantages and disadvantages for the disabled users community. • The benefits are the same as those that apply to non-disabled users • The disadvantages are mainly that the user may not have the physical (eye-hand) coordination or visual skills.

  20. Graphic User Interface • Adaption for alternative input or output is is often difficult and, and adaptations may need to be redone when the underlying operating system is changed.

  21. Graphic User Interface • The GUI presents difficult problems to the blind computer user. • Early computer systems used a Command Line Interface (CLI) in which commands were typed in and then executed by the computer. • Early screen readers were able to access the memory buffer and copy the text from the screen to a speech synthesizer.

  22. Graphic User Interface • The GUI cannot be used in the same way, since it uses Visual Metaphors. • Which are familiar objects to represent actions in the computer. • For example, to delete a file you can drag it into the trash can. • A filing cabinet can be used to represent a disk drive.

  23. Graphic User Interface • The GUI represents several problems for the blind user • It is difficult to represent the visual elements in an alternative mode. How could a text-to-speech or speech synthesis program represent this complexity?

  24. Graphic User Interface • Most icons have text labels with them, and one adaptation approach is to intercept this label and send it to a text-to-speech system.

  25. Graphic User Interface • Another issue concerns the fact that the GUI is spatially organised. • Since auditory information is organised in a temporal (time-based) fashion, this poses challenges. • It is difficult to express the location of the mouse pointer by speech alone. The only exception being the extremities of the screen, e.g., top of screen, right border.

  26. Graphic User Interface • Additionally multiple, overlapping windows make sense visually, but can be complex to describe in an auditory context.

  27. Graphic User Interface • The Microsoft Application Programming Interface for accessibility is a set of programs that provide alternative ways to store and access information about the contents of the computer screen. • The accessibility API also includes software driver interfaces that provide a standard mechanism for accessibility utilities to send information to speech devices or refreshable Braille displays.

  28. Non-speech Sound Cues • Four types of non-speech sound cues that represent visual icons • Auditory icons • Earcons • Hearcons • Beacons

  29. Non-speech Sound Cues:Auditory icons • These are everyday sounds used to represent graphical objects, e.g. A window might be represented by the sound of tapping a glass pane, a text box could be represented using the sound of a typewriter. • The Screen Access Model and Windows sound libraries are used in some applications.

  30. Non-speech Sound Cues:Earcons • These are abstract auditory labels that do not necessarily have a semantic relationship to the object that they represent. • An example of an earcon is a musical note or string of notes played when a file, window, or program is open or closed. • Different musical instruments may be used to represent different actions, such as a trumpet representing opening a file, and a drum representing closing a file.

  31. Non-speech Sound Cues:Hearcons • These are either nature sounds or musical works. • Examples are running rivers or birds tweeting. • Location dependent • These typically prove to be ineffective in user tests.

  32. Non-speech Sound Cues:Beacons • These are a combination of different auditory labels to convey a series of actions. • It usually employs Gestalt presentation • Similarity • Proximity • Continuation • Etc.

  33. Reading Aids for People with Visual Impairments • Three major problems facing the visually impaired; • Access to printed reading materials • Orientation and mobility (moving safely and easily) • Access to computers and the internet

  34. Reading Aids for People with Visual Impairments • Three major problems facing the visually impaired; • Access to printed reading materials • Orientation and mobility (moving safely and easily) • Access to computers and the internet

  35. Interesting PhD Thesis • “Interaction with Sound: Explorations beyond the Frontiers of  3D virtual auditory Environments” •

  36. Magnification Aids • Three factors that effect visual performance • Size • Spacing • Contrast • Magnification can be of three types • Vertical (increasing the size of the text) • Horizontal (increasing the spacing of the text) • Both

  37. Magnification Aids

  38. Screen Magnifiers • Screen Magnifiers • Three basic modes of operation • Lens magnification: A magnifier is placed over an area of the screen and that area is increased • Part-screen magnification: Almost exactly the same as “lens magnification” except magnification happens in a separate window • Full-screen magnification: Enlarge the entire screen

  39. Automatic Reading of books • They need the three components mentioned at the start • An environmental interface • An information processor • A user display

  40. Automatic Reading of books • They need the three components mentioned at the start • An environmental interface: OCR • An information processor: Text-to-Speech • A user display: Speaker

  41. Automatic Reading of books Text-to-speech Voice Synthesiser Camera Or Scanner Optical Character Recognition Text-to-Braille Refreshable Braille Display

  42. Recorded Audio Material • CDs and CD-ROMs • E.g. Recording for blind and dyslexic • • E.g. National Library Service for the Blind •

  43. Recorded Audio Material • DAISY CONSORTIUM • • This group has develop an international standard for digital talking books, which includes production, exchange, and use of digital books. • The DAISY standard is hardware independent and operating system independent.

  44. Screenreaders • I know Ciaran is covering this in Accessible Web Design, so the quickest thing to say is look at the Wikipedia page: • “Comparison of screen readers”

  45. Screenreaders

  46. Pictures of AT Devices for Visual Impairment

  47. Access to Print Material • Large print books • Audio Books • Desk top magnifiers

  48. Access to Writing for Students with Visual Impairments

  49. Computer Accessfor Students with Visual Impairments • Lower screen resolution • High contrast settings • Screen magnification software • Screen reader software • Scan and read software • Refreshable Braille output

  50. Check out the OATS site •